Construction and Lithium-Ion Battery Performance of MoS₂/PDA/SnS₂ Nanotubes Based on a PDA Confinement Structure

Molybdenum disulfide (MoS₂) and tin disulfide (SnS₂), known for their high theoretical capacities and large interlayer spacings, have been widely used as anode materials in lithium-ion batteries. The composite materials formed between them are an even greater research focus. However, conventional MoS₂/SnS₂ composites suffer from severe volume changes and structural fragmentation during the charge–discharge cycles, leading to rapid decay in specific capacity, which hinders the cycling stability that MoS₂/SnS₂ composite electrodes should ideally possess. In this work, a novel MoS₂/PDA/SnS₂ nanotube was designed and synthesized. Specifically, a hollow MoS₂ nanotube was coated with a polydopamine (PDA) layer as a confinement structure to prevent the structural breakdown of MoS₂ in subsequent processes. Subsequently, MoS₂/PDA/SnS₂ nanotubes were successfully prepared by growing a layer of SnS₂ nanosheets on the polydopamine (PDA) surface through a hydrothermal method. This preparation method not only prevented the rupture of the hollow tubular structure but also facilitated the growth of SnS₂ nanosheets through the free dopamine molecules. This superior structural design significantly enhances the stability of the material while also improving its electrical conductivity. The composite electrode demonstrates excellent cyclability, retaining a specific discharge capacity of 1330.2 mAhg⁻¹ over 90 cycles at 0.1 A g⁻¹. Notably, even after 800 cycles at a high rate of 1 A g⁻¹, the capacity remains virtually unchanged at 1366.3 mAhg⁻¹.